I've paid my entrance fee and am running it for the National rheumatoid arthritis society, which is a charity really close to my heart. So in addition to having a fitness/time goal I have a good incentive to knuckle down and train hard.
During the half marathon I learned pretty quickly that stopping or walking was not an option as I probably wouldn't get going again! My legs felt like sandbags by the end and I don't think I've ever pushed myself beyond my limits like that before. I ran to the point of exhaustion, way beyond what I thought I was capable of and was still standing at the end.
But yes I have definitely caught the race bug.